(a) Field of the Invention
The present invention relates to a variable valve lift apparatus that adjusts a valve lift amount in response to an operational state of an engine.
(b) Description of the Related Art
A typical combustion chamber of an automotive engine is provided with an intake valve for supplying the air/fuel mixture and an exhaust valve for expelling the burned gas. The intake and exhaust valves are opened and closed by a valve lift apparatus connected to a crankshaft.
A conventional valve lift apparatus has a fixed valve lift amount due to a fixed cam shape. Therefore, it is impossible to adjust the amount of a gas that is being introduced or exhausted.
If the valve lift apparatus is designed for low driving speeds, the valve open time and amount are not sufficient for high speeds. On the other hand, if the valve lift apparatus is designed for high speeds, the opposite is true.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.